Syllable division and stress derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
long-acting is an adjective meaning "active over a long period of time". It carries one recorded sense.
active over a long period of time
Definitions, synonyms and semantic relations for long-acting come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.